WPF border animation not working - wpf

Question

I am trying to put an animation on a border as follows
<LinearGradientBrush x:Key="RedButtonBrushUp" StartPoint=".5,0" EndPoint=".5,1">
<GradientStop Color="#ffaaaa" Offset="0"/>
<GradientStop Color="#cc6666" Offset="0.6"/>
<GradientStop Color="#bb2222" Offset="1"/>
</LinearGradientBrush>
<LinearGradientBrush x:Key="ButtonBrushUp" StartPoint=".5,0" EndPoint=".5,1">
<GradientStop Color="#aaccff" Offset="0"/>
<GradientStop Color="#7799ff" Offset="0.6"/>
<GradientStop Color="#555599" Offset="1"/>
</LinearGradientBrush>
<Border x:Name="BorderUp" BorderThickness="2,2,2,2" CornerRadius="4,4,4,4" Background="{StaticResource RedButtonBrushUp}">
<Border.Triggers>
<EventTrigger RoutedEvent="Border.Loaded">
<BeginStoryboard>
<Storyboard >
<DoubleAnimation Storyboard.TargetName="BorderUp"
Storyboard.TargetProperty="Background"
RepeatBehavior="Forever"
AutoReverse="True"
To="{StaticResource ButtonBrushUp}"
Duration="0:0:0.5" ></DoubleAnimation>
</Storyboard>
</BeginStoryboard>
</EventTrigger>
</Border.Triggers>
</Border>
But it says {StaticResource ButtonBrushUp} is an invalid type for this. What am I doing wrong?

Answer 1

The To can't accept such a change needed for the gradient brush stops.
Here is a working example of what you are trying to do
<Window.Resources>
<Storyboard x:Key="OnLoaded1">
<ColorAnimationUsingKeyFrames Storyboard.TargetProperty="(Border.BorderBrush).(GradientBrush.GradientStops)[1].(GradientStop.Color)" Storyboard.TargetName="myBorder">
<EasingColorKeyFrame KeyTime="0:0:1" Value="#FFC53838"/>
</ColorAnimationUsingKeyFrames>
</Storyboard>
</Window.Resources>
<Window.Triggers>
<EventTrigger RoutedEvent="FrameworkElement.Loaded" SourceName="myBorder">
<BeginStoryboard Storyboard="{StaticResource OnLoaded1}"/>
</EventTrigger>
</Window.Triggers>
<Grid>
<StackPanel x:Name="stackPanel" Orientation="Vertical" HorizontalAlignment="Center">
<Border x:Name="myBorder" Background="#99FFFFFF" BorderThickness="3"
Margin="0,60,0,20" Padding="20" >
<Border.BorderBrush>
<LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
<GradientStop Color="Black" Offset="0"/>
<GradientStop Color="White" Offset="1"/>
</LinearGradientBrush>
</Border.BorderBrush>
<TextBlock>
This example shows how to have a border change color after an initial load.
</TextBlock>
</Border>
</StackPanel>